After the Wright brothers took off from Kitty Hawk in 1903, one of their primary goals was to sell the airplane to the U.S. Army as a machine for scouting. After World War I broke out, the airplane quickly proved to be a key innovation in aerial reconnaissance. When airspace became valuable in warfare, that too became contested: within a few weeks, armed versions of scout airplanes had appeared.

But developing an airplane for aerial fighting involved one important detail: where and how to mount the armament; after early trials with pistols and shotguns, armament consisted of one or two machine-guns. Two-seater airplanes had flexible machine-gun mounts where the gun could be pointed in different directions by the gunner. Single-seat airplanes with one pilot needed to have a fixed gun: it could be mounted to fire at an angle from the direction of travel, or it could sit on the top wing shooting over the arc of the prop, or it could be right in front of the pilot, perhaps bolted on the cowling and shooting through the arc of the propeller (and sometimes hitting the propeller). None of these were ideal. It wasn’t until June 1915 that the German company Fokker designed and built a mechanism that synchronized the firing of the gun with the movement of the propeller, and with that mechanism installed on the Fokker Eindecker monoplane, the purpose-built fighter aircraft was born.

In the issue of Scientific American from 100 years ago, a front-page article explained in detail the workings of the new Fokker device. The article is detailed and accurate, (and I am curious about how the information got past the military censors—even non-German ones):

“It seems a mechanical anomaly that many of the battleplanes flying over the fighting forces of Europe should be equipped with machine guns that fire through the path of the revolving propeller. Yet this condition has been brought about in the development of the fast and highly-flexible battleplanes, such as the single-seater Morane of the Allies and the single-seater Fokker of the Germans.”

“In certain of the French machines the gun is fired continuously through the path of the revolving propeller blades, no attempt being made to select such times for the firing when the blades are not in the path of fire. The portion of each propeller blade coming in direct line with the muzzle of the gun is sufficiently armored so that the bullets that strike are deflected without causing any damage, and it is estimated that under no circumstance does the wastage of fire exceed 30 per cent.”

 “The machine gun of the Fokker is of the Maxim type and is immovably affixed above the engine cowl and slightly to the right, so that its line of fire passes through the path of the revolving propeller in front. In sighting his gun the pilot, as previously stated, maneuvers his aeroplane until the sights register on the target.”

“Instead of the machine gun being fired by pulling the trigger, as in usual practice, the trigger is operated by a cam [on the engine shaft] and a transmission mechanism under the control of the pilot.”


The views expressed are those of the author and are not necessarily those of Scientific American.

Our full archive of the war, called Scientific American Chronicles: World War I, has many articles from 1914–1918 on technology advances in the First World War. It is available for purchase at